Microbial Colonies of Pu’er Tea – new research

I’ve been talking / teaching / writing about the importance of the origin and cultivation of the microbial colonies within Pu’er tea for years,as they’re responsible for everything from “aging” rate to flavor profiles. (Reminder: all tea ages at the same rate of 1 year per year)

Yet, outside of the Institute, I’ve gotten some pushback;
including some crazy counter arguments like  pu’er is never actually fermented, or that there is no effect on colony strains from the factory / plantation / forest, or that the steaming process kills of the microbial colonies during compression (it doesn’t).

 

This new paper (June 2016) does a good job of showing just how important the microbiological colonies and inoculations are in determining arability, flavor profile, and quality of Shou Pu’er.

The Microbiome and Metabolites in Fermented Pu-erh Tea as Revealed by High-Throughput Sequencing and Quantitative Multiplex Metabolite Analysis

 

Abstract

Pu-erh is a tea produced in Yunnan, China by microbial fermentation of fresh Camellia sinensis leaves by two processes, the traditional raw fermentation and the faster, ripened fermentation. We characterized fungal and bacterial communities in leaves and both Pu-erhs by high-throughput, rDNA-amplicon sequencing and we characterized the profile of bioactive extrolite mycotoxins in Pu-erh teas by quantitative liquid chromatography-tandem mass spectrometry. We identified 390 fungal and 629 bacterial OTUs from leaves and both Pu-erhs.
Major findings are: 1) fungal diversity drops and bacterial diversity rises due to raw or ripened fermentation, 2) fungal and bacterial community composition changes significantly between fresh leaves and both raw and ripened Pu-erh, 3) aging causes significant changes in the microbial community of raw, but not ripened, Pu-erh, and, 4) ripened and well-aged raw Pu-erh have similar microbial communities that are distinct from those of young, raw Ph-erh tea.

Twenty-five toxic metabolites, mainly of fungal origin, were detected, with patulin and asperglaucide dominating and at levels supporting the Chinese custom of discarding the first preparation of Pu-erh and using the wet tea to then brew a pot for consumption.